1. Field of the Invention
The present invention relates to a piezoelectric actuator which is available to obtain mechanical displacement by displacement of piezoelectric element.
2. Description of the Related Art
Presently, as a piezoelectric actuator, a rotation type represented by a type using progressive oscillating wave and a linear type represented by a type having clamping mechanism are known. The rotation type and the linear type are properly used depend on motion track, size, accuracy requirement and the like of a member which is a driven object. A linear type piezoelectric actuator can be used as a driving source for any members acting linear motion particularly, it is preferable, for example, a lens barrel with lenses which linearly moves in a body tube for auto focusing.
As a linear type piezoelectric actuator according to conventional art, for example, it is known described in JP Patent Publication No. 55-100059. Such the linear type piezoelectric actuator with respect to the conventional art comprises a structure to hold a first to a third stacked piezoelectric elements as H-shape by a pair of T-shaped cross-sectional supporting member. Said linear type actuator is that first stacked type piezoelectric elements are stacked towards moving direction which are available to expansion, contrary this, second piezoelectric elements and third piezoelectric elements are stacked toward a direction orthogonal to said moving direction which are available to expansion towards said orthogonal direction. Said linear type actuator can back and forth movement on a guide rail by acting looping movement according to expansion the first stacked type piezoelectric elements with clamping the guide rail by the second or the third stacked type piezoelectric elements.
However, there is a problem that the piezoelectric actuator according to the above conventional art is difficult to minimize its size due to complexity of its shape and mechanism. Also, stacking directions of the respective piezoelectric elements are orthogonal respectively adds complexity wiring, at this point, it is hard to minimize.